KWInequalityType declaration is incompatible with iOS5 SDK; does not need to be public.

The NS_ENUM macro used to define the KWInequalityType is only available in the iOS6 and MacOS 10.8 SDK,
but Kiwi would otherwise work fine at least back to the iOS5 and MacOS 10.6 SDKs (and possibly earlier). Further, the enum is used only internally within the KWInequalityMatcher class so it does not to be in the public interface. Moving the definition to the top of the .m file solves both issues.